1. Field of the Invention
The present invention relates to a curable resin composition useful as a material for an optical apparatus/an optical component, an insulator material for an electronic apparatus/an electronic component, and a coating material, a hardened material thereof, and an optical semiconductor apparatus.
2. Description of the Related Art
An optical semiconductor apparatus typified by a light-emitting diode (LED) is generally characterized by low power consumption and long life span. For this reason, the optical semiconductor apparatus is widely used for applications such as a backlight for a portable telephone, a backlight for a liquid crystal television, a lighting for an automobile, a lighting equipment, and a signboard.
In particular, since an LED apparatus is widely used for an application of an outdoor lighting and an application for an automobile, a resin composition used as a LED device sealing material, an electronic apparatus insulator material, or a coating material is required to have high durability. Therefore, the resin composition is required to have a performance in which a crack is unlikely to occur under a severe temperature cycle, resistance to discoloration by long-time exposure to high temperature is excellent, and transmission of gas such as SOx can be prevented.
In general, the luminescence characteristics of an optical semiconductor apparatus are determined by a combination of a light-wavelength transforming material (hereinafter referred to as phosphor) with an optical semiconductor device. An optical semiconductor apparatus having color rendering properties for various intended purposes depending on the weight ratio of the phosphor to be mixed can be obtained. However, it is difficult that a light-emitting apparatus having stable color rendering properties is consecutively fabricated in the fabrication of such an optical semiconductor apparatus. Specifically, a predetermined amount of sealant in which a phosphor is added to a curable resin composition having a high transparency is filled into a package substrate having an optical semiconductor device mounted thereon and a concave portion subjected to wire bonding using a dispensing apparatus, and is hardened to fabricate an optical semiconductor apparatus. In this process, since the specific gravity of the added phosphor is larger than that of the curable resin composition, the sealant is precipitated at the bottom of a container due to the weight of the phosphor itself over time. This is because the general phosphor is a material having a density of about 4 to 6 g/cm3 and an average particle size of 20 μm or less and the curable resin composition has a density of about 1 g/cm3. Therefore, the precipitation of phosphor over time during the sealing process of the fabrication process can be easily understood. Accordingly, when a sealant containing a phosphor is filled into a package substrate, the deviation state of the phosphor is changed at the early and late stages of the fabrication, and there is a phenomenon in which the content of the phosphor in the sealant is large at the early stage, and the content of the phosphor in the sealant is small at the late stage. This is because an increase or a decrease in the content of the phosphor is involved in the amount of light to be transformed. Thus, the color rendering properties designed are changed, and therefore there is a problem in which a product having stable characteristics cannot be obtained.
In Patent document 1 as an example of solving the problem, silicone rubber spherical fine particles having an average particle size of 0.1 to 100 μm are added to a thermosetting resin composition. However, the process has a problem in which the silicone rubber spherical fine particles and a surface treatment agent have low heat resistance and light resistance in many cases. Further, Patent document 2 has proposed a process for dispersing nanoparticles having an average particle size of 1 nm or more and 25 nm or less at a nano scale to prevent the precipitation of a phosphor.
The proposed processes achieve an effect of preventing the precipitation of a phosphor in a curable resin composition having a comparatively high viscosity, but cannot achieve the effect in the curable resin composition having a low viscosity. Thus, the color rendering properties designed are changed, and therefore a problem in which a product having stable characteristics cannot be obtained is not solved.
Accordingly, a curable resin composition for an optical semiconductor apparatus is required in which when a sealant obtained by dispersing a phosphor in a curable resin composition having a low viscosity is filled into a package substrate, the deviation state of the phosphor is not changed at the early and late stages of the fabrication, the amounts of the phosphor to be contained at the early and late stages are the same, and the color rendering property can be stably maintained.